This page contains information about the trailer released on the 2nd November 2011 of GTA V.
The trailer shows a lot of vehicles. It has Cars, Airplanes and more. For more information check the Transportation page.
In the video there is also a flash of a house being sold, this could indicate that there will be a possibility to buy houses and/or assets in the game just like in San Andreas. Or maybe there is a "economic crisis", as there is a beggar just after that screen. It is most likely a house being forclosed, as one of the focuses of the trailer is poverty in Los Santos.
There is also a Golf Course. It may be possible to Golf in the game.
There are fitness devices in the trailer so it could be that you are able to train yourself, just like in San Andreas. And increase stamina and such.